I've been traveling internationally quite a bit this year, and often find myself scheduling meetings with people in a variety of locations. One of the challenges is mapping the time zones correctly so that everyone actually shows up at the right time.
I've tried a variety of methods to resolve this, but have found an iOS app that is just great for this. The app is called "AllHours" and it makes time zone coordination a snap.
In the interface, select the desired time in one time zone (generally the one you're in) and it will adjust the time in the others to show you what the various local times will be.
You can then tap on the little envelope button (see the screen shot) to open your email client with a pre-composed list of the cities and the local dates and times you've selected in the UI. That makes it easy to send proposed meeting times to others to review.
If you're ready to schedule the meeting, tap on the little calendar icon and it will open a meeting request for the time you've selected.
AllHours is a great (free) solution for iOS. If you've found a good app like this for other platforms, please leave a comment with your suggestions.